Clavulactone (1) is an unusual dolabellane diterpene isolated from the Pacific soft coral Clavularia viridis. Its unprecedented tricyclic structure and antitumor activity motivate the studies described in this proposal. Daunting challenges posed by 1 include the remote stereocenter at C8, the quaternary carbon center at C1, and the potentially strained eleven-membered medium ring. Our synthesis plan incorporates macrocyclic stereocontrol, catalytic asymmetric conjugate addition of an alkyl metal reagent, and a fascinating intramolecular hetero Diels-Alder reaction. [unreadable] [unreadable]